This invention relates to fiber optic scopes and, in a particular embodiment, to intubation scopes. Advantageously, this invention utilizes plastic optical fibers to enhance the safety and efficacy of procedures performed with these novel fiber optic scopes, while simultaneously reducing the costs. Additionally, the scopes of the subject invention can, optionally, utilize a sheath which can reduce the amount of cleaning, i.e., sterilization, required between uses and thereby reduce the costs of use.
It is frequently necessary in medical procedures to insert an endotracheal tube into the trachea of a patient for the purpose of performing diagnostic tests or for the introduction of some means of ventilation, oxygenation, and/or airway protection. Even in the best situations, intubation is often difficult and can give rise to complications. In many patients, establishment of the airway is particularly difficult due to morphologic anomalies such as a large tongue, excessive pharyngeal or laryngeal soft tissue, or tracheal displacement, as well as physiologic events such as laryngospasm, regurgitation of gastric materials, bleeding, or foreign bodies aspiration. These morphologic anomalies and/or events make it difficult to visualize the posterior pharyngeal area and larynx with conventional laryngoscopic maneuvers. In emergency situations, attempts to intubate such patients are difficult and time consuming. Inability to expeditiously intubate the patient and protect the airway can lead to significant hypoxemia, myocardial ischemia, and brain injury. Cases of death have also been related to complications caused by the inability to quickly and clearly see the larynx and trachea.
Proper intubation requires positioning the tip of the tracheal tube within the trachea, midway between the patient's vocal cords and carina. Direct laryngoscopy in many instances is sufficient to intubate the patient, but does not permit the precise confirmation of tip location or tracheal inspection.
If the tracheal tube is not inserted far enough past the vocal cords, the tube may become dislodged and prove to be ineffective in supporting adequate artificial ventilation. Further, the tube may inadvertently end up in the esophagus. Esophageal intubations, resulting from either dislodgement or incorrect initial placement have led to severe morbidity and even death. At the other extreme, if inserted too far and beyond the carina, the tube may only permit ventilation of one lung (as opposed to both lungs). Thus, correct tube placement is essential in order to properly ventilate the patient.
Even the most skilled anesthesiologist may encounter what is commonly referred to as a "difficult" airway. This occurs in about 5% of all operating room intubations, with an even higher incidence of an inability to fully visualize the glottic opening. The incidence level is significantly higher in other areas of the hospital and prehospital environment. Although presurgical examination of the jaw, teeth, mouth opening and neck motion assists in gauging the degree of difficulty likely to be encountered at intubation, not all difficult intubations can be identified in advance. There is always the unexpected difficult airway, discovered only at the time of intubation. In emergency situations, there is little if any time to perform an airway assessment prior to attempting intubation. Thus, all emergency intubations are considered "difficult" intubations.
There are a number of techniques used to assist in difficult intubations. These include laryngoscopy, with or without axial cervical traction, fiberoptic bronchoscopy, with or without a transtracheal retrograde wire guide, blind nasal and the lighted stylet techniques.
Fiberoptic bronchoscopy is considered by many as the "gold standard" for viewing the airway and properly positioning a tracheal tube. The complexity of operating and cost of buying, maintaining, cleaning, and replacing existing glass fiberoptic systems, which are fragile, are major factors preventing greater usage of bronchoscopy.
The retrograde wire technique involves placing a needle into the cricothyroid space and advancing a guide wire through the needle and upward through the glottic opening between the vocal cords and pharynx until it emerges from the nose or mouth. After the wire is localized, a fiberoptic bronchoscope or tracheal tube is advanced over the wire into the larynx. This technique is not recommended in emergency situations. Major negative concerns associated with this technique are its invasive nature and the risk for bleeding and infection in the trachea. The wire can also cause injury to the tracheal tissue and/or vocal cords.
A lighted stylet incorporates aspects of both the fiber scope and retrograde wire techniques. It is essentially a standard stylet with a bright light at the distal end. This technique provides only indirect transcutaneous illumination of the trachea. Direct visualization is not possible when using a lighted stylet.
Fiberoptic intubating scopes with cameras and/or eyepieces for viewing that which is illuminated by the fiber optic system have previously been described. See, for example, U.S. Pat. Nos. 3,776,222; 4,742,819; and 5,363,838. Current fiber optic scopes, for example, intubation scopes and associated systems for imaging the human airways, typically use glass optical fibers. Unfortunately, these intubation scopes and associated systems utilizing glass optic fibers are expensive to purchase, clean, and store. Additionally, the glass optical fibers within these scopes are prone to breaking thereby shortening the life of the scopes.